WO2013018724A1

WO2013018724A1 - Cutting insert and rotating cutting tool

Info

Publication number: WO2013018724A1
Application number: PCT/JP2012/069227
Authority: WO
Inventors: 新城　裕二; 勇齊藤
Original assignee: 株式会社タンガロイ
Priority date: 2011-07-29
Filing date: 2012-07-27
Publication date: 2013-02-07
Also published as: JP5790765B2; CN103582538A; JPWO2013018724A1; US20130142578A1; EP2737969A4; EP2737969B1; CN103582538B; US9289835B2; EP2737969A1

Abstract

According to one embodiment of the present invention, provided is a cutting insert (10) having two curved first cutting blades (30, 32) on the side of a first end surface (12) and also having two curved second cutting blades (34, 36) on the side of a second end surface (14) located on the side opposite to the first end surface (12). At the ridge line portions formed at the intersections of the first end surface (12) and side surface portions (20, 24), the respective first cutting blades (30, 32) are formed by being curved in a direction orthogonal to an axial line (A) extending so as to pass through the first and second end surfaces. At the ridge line portions formed at the intersections of the second end surface (14) and the side surface portions (20, 24), the respective second cutting blades (34, 36) are formed by being curved in a direction orthogonal to the axial line (A).

Description

Cutting inserts and rotary cutting tools

The present invention relates to a cutting insert and a rotary cutting tool to which the cutting insert is detachably mounted. In particular, the present invention relates to cutting inserts and rotary cutting tools used to form gear tooth spaces.

Conventionally, as one of the cutting tools for manufacturing gears, a blade cutting type rotary cutting tool has been used. In this tool, cutting inserts are assembled from the side end surface side of the tool body to the insert mounting seats disposed on both end surfaces of the tool body with tightening screws. The cutting edge shape of the tool has the same shape as the gear tooth groove, and when the groove is machined with the tool, the cutting edge shape is directly transferred to the work material as the tooth shape.

An example of a cutting insert used for such a rotary cutting tool for gear cutting is disclosed in Patent Document 1. Here, reference is made to FIG. 26 and FIG. 27 schematically showing the cutting insert of Patent Document 1. FIG. In the cutting insert 1 of FIGS. 26 and 27, the intersecting ridge line portion between the upper surface 2 and the side surfaces 3 and 4 extends to the side portion 5, and this intersecting ridge line portion is formed as a series of smooth cutting edges. The side surfaces 3 and 4 are formed so as to function as rake surfaces, and the lower surface 6 is formed as an insert seating surface. In a side view as shown in FIG. 27, the intersecting ridge line portion between the upper surface 2 and the side surfaces 3 and 4 is formed in a convex shape toward the outer side of the insert. Therefore, the upper surface 2 has a curved surface shape according to the convex shape of the intersecting ridge line portion. On the other hand, since the lower surface 6 is an insert seating surface, it has a flat shape. The intersecting ridge line portion between the upper surface 2 and the side surfaces 3 and 4 is formed to have an involute curve shape. Therefore, by using this cutting insert for cutting, this involute curve shape can be transferred to the work material as a tooth profile. In this cutting insert, cutting edges are formed only on the upper surface side, and the number of cutting edges that can transfer the involute curve shape to the work material is two.

In FIG. 28, the cutting insert 1 is attached to the both end faces of the tool body 7 of the rotary cutting tool, and the cutting tool 1 is rotated to feed the work material. The process of processing one by one is schematically shown as an example. In FIG. 28, two cutting inserts 1 are shown to face each other, but in reality, these cutting inserts 1 are arranged at a predetermined interval in the circumferential direction of the tool body.

JP 2005-66780 A

Now, in the cutting insert for gear cutting, it is desired to increase the number of cutting edges capable of transferring the involute curve shape to the work material more than before. This is because, in order to form an involute curve-shaped cutting edge in a cutting insert, high technology and accuracy are required, the manufacturing cost of the cutting insert increases, and as a result, the unit price of the cutting insert is high at present.

As a measure to increase the number of usable cutting edges more than before, it is conceivable to improve the cutting insert of Patent Document 1 that uses one side to a cutting insert that uses both sides. In the cutting insert improved in this way, a cutting edge is formed also on the lower surface 6 side of the cutting insert 1 shown in FIGS. 26 and 27, and not only the upper surface 2 but also the lower surface 6 has a convex shape. In this form of cutting insert, it is possible to use four cutting edges in combination with the upper and lower surfaces. However, in this case, both the upper surface and the lower surface serving as the insert seating surfaces are convex curved surfaces that follow an involute curve. In order to mount the cutting insert having such a shape on the tool body, the shape of the bottom wall surface of the insert mounting seat of the tool body must be a concave curved surface that follows an involute curve. However, since it takes very much labor and cost to form such a concave curved surface on the bottom wall surface of the insert mounting seat with a cutting tool such as an end mill, such an insert mounting seat is not practical. Even if it is attempted to form the insert mounting seat as such, it is difficult to accurately form such a concave curved surface on the bottom wall surface of the insert mounting seat of the tool body. A problem will remain in the mounting stability of the cutting insert in the seat.

The present invention does not have to have a specific curved surface corresponding to the shape of the cutting edge on the bottom wall surface of the corresponding insert mounting seat to be mounted while having a specific curved cutting edge on each of the upper and lower surface sides. An object of the present invention is to provide a cutting insert and a cutting tool to which the cutting insert is attached.

According to the first aspect of the present invention, the first end surface and the second end surface which are opposite to each other, and the peripheral side surface extending between the first end surface and the second end surface, the two side surfaces In the cutting insert, the first cutting edge having two curved shapes, wherein the first cutting edge is defined by an axis extending through the first end surface and the second end surface. The one cutting edge is formed so as to extend along an intersecting ridge line portion between the first end surface and one of the two side surface portions, and the one side surface portion functions as a rake face. The other first cutting edge extends so as to extend along the intersecting ridge line portion between the first end surface and the other side surface portion of the two side surface portions, and the other side surface portion functions as a rake face. Each first cutting edge is formed with a side portion associated with the first end surface; In the intersecting ridge line portion, a first cutting edge and a second cutting edge having two curved shapes that are curved in a direction perpendicular to the axis, and one second cutting edge is the second end face And one of the two side surface portions so as to extend along an intersecting ridge line portion, and the one side surface portion functions as a rake face, and the other second cutting edge is The second end surface and the other side surface portion of the two side surface portions extend along the intersecting ridge line portion, and the other side surface portion functions as a rake face, The cutting edge is provided with a second cutting edge, which is formed by being curved in a direction perpendicular to the axis at an intersecting ridge line portion between the second end face and the side surface portion related to the second end face. The

According to such a configuration, the curved first cutting edge can be formed on the first end face side, and the curved second cutting edge can be formed on the second end face side. And each 1st cutting edge is curved and formed in the direction orthogonal to an axis line in the intersection ridgeline part of a 1st end surface and a side part, and each 2nd cutting edge is the intersection ridgeline of a 2nd end surface and a side part. Since the portion is curved in a direction perpendicular to the axis, the degree of freedom in designing the surface shape of the first end surface and the second end surface is not substantially limited to the curved shape of the first cutting edge and the second cutting edge. . Therefore, for example, the first end surface and the second end surface can each be a flat surface. Therefore, the bottom wall surface of the corresponding insert mounting seat to which the cutting insert of the first aspect is attached does not need to have a specific curved surface adapted to the shape of the cutting edge.

Preferably, the first cutting edge is formed to have a predetermined first curved shape when the cutting insert is viewed from the side facing the first end face, and the second cutting edge faces the second end face. The cutting insert may be formed so as to have a predetermined second curved shape when viewed from the side. Preferably, the first cutting edge and the second cutting edge that are related via the common side surface portion of the two side surface portions may be arranged to be plane-symmetric.

The first cutting edge and the second cutting edge can each be formed in a convex curve shape so as to protrude outward. Alternatively, each of the first cutting edge and the second cutting edge may be formed in a concave curved shape so as to be recessed inward.

Preferably, the first cutting edge and the second cutting edge may each be formed to have an involute curve shape. Alternatively, the first cutting edge and the second cutting edge may each be formed so as to have a curved shape configured by combining a plurality of curved portions having different curvatures. For example, when the first cutting edge and the second cutting edge are each formed at least partially so as to have a convex curve shape formed by joining the first curved portion and the second curved portion, respectively. When the curvature radius of the first curve portion is R1, the curvature radius R2 of the second curve portion is preferably in the range of 0.4R1 or more and less than 1.0R1. Alternatively, when the first cutting edge and the second cutting edge are each formed at least partially so as to have a concave curved shape formed by combining the first curved portion and the second curved portion, When the curvature radius of the first curve portion is R1, the curvature radius R2 of the second curve portion is preferably in the range of 1.2R1 or more and less than 2.3R1. Note that the length of the second curve portion is preferably longer than the length of the first curve portion.

Preferably, a recess is formed on the peripheral side surface.

More preferably, in the insert mounting seat of the tool body configured to rotate around the rotation axis, the cutting insert has a predetermined inclination with respect to a plane defined to be orthogonal to the rotation axis, The first end surface or the second end surface is detachably attached as a seating surface.

According to a second aspect of the present invention, there is provided a rotary cutting tool comprising a tool body having two side end surfaces opposite to each other, the tool body configured to rotate around a rotation axis. A first insert mounting seat disposed on the tool body on one side end surface side of the two side end surfaces, the first insert mounting seat to which the cutting insert as described above is mounted, and two side end surfaces A second insert mounting seat disposed on the tool body on the other side end surface side, the second insert mounting seat to which the cutting insert as described above is mounted, and the first end surface of the cutting insert Has a function as an insert seating surface that contacts the bottom wall surface of the first insert mounting seat, and the second end surface of the cutting insert is an insert that contacts the bottom wall surface of the second insert mounting seat. When defining a plane having a function as a seating surface and extending perpendicular to the rotation axis, the bottom wall surface of the first insert mounting seat is formed with a first predetermined inclination with respect to the plane, A rotary cutting tool is provided in which the bottom wall surface of the second insert mounting seat is formed with a second predetermined inclination with respect to the plane.

When the cutting insert is a cutting insert formed such that the first cutting edge and the second cutting edge have a curved shape formed by joining a plurality of curved portions having different curvatures, A portion extending between one curved portion of the first cutting edge and one curved portion of the second cutting edge in the side portion functions as a contact surface portion, and the side wall surface of the first insert mounting seat and the second Each of the side wall surfaces of the insert mounting seat may be formed with a convex contacted portion that can contact the corresponding contact portion.

When the recess is formed on the peripheral side surface of the cutting insert, the side wall surface of the first insert mounting seat and the side wall surface of the second insert mounting seat are respectively formed with protrusions that can be engaged with the recess of the cutting insert. It is good to be.

FIG. 1 is a top view of a cutting insert according to the first embodiment of the present invention. FIG. 2 is a side view of the cutting insert of FIG. FIG. 3 is a perspective view of the cutting insert of FIG. FIG. 4 is a front view of the rotary cutting tool according to the first embodiment of the present invention to which the cutting insert of FIG. 1 is attached. FIG. 5 is a side view of the rotary cutting tool of FIG. FIG. 6 is a schematic diagram relating to the insert mounting seat with the rotary cutting tool of FIG. 5, and is a diagram showing a simplified inclination of the bottom wall surface of the insert mounting seat. FIG. 7 is a partially enlarged view of the rotary cutting tool of FIG. FIG. 8 is a top view of the cutting insert according to the second embodiment of the present invention. FIG. 9 is a perspective view of a cutting insert according to the third embodiment of the present invention. FIG. 10 is a side view of the cutting insert of FIG. FIG. 11 is a partially enlarged view of the insert mounting seat of the tool body of the rotary cutting tool of the third embodiment of the present invention to which the cutting insert of FIG. 9 is attached. FIG. 12 is a top view of a cutting insert according to the fourth embodiment of the present invention. FIG. 13 is a side view of the cutting insert of FIG. FIG. 14 is a perspective view of the cutting insert of FIG. FIG. 15 is a front view of a rotary cutting tool according to the fourth embodiment of the present invention, to which the cutting insert of FIG. 12 is attached. FIG. 16 is a side view of the rotary cutting tool of FIG. FIG. 17 is a perspective view of a cutting insert according to the fifth embodiment of the present invention. FIG. 18 is a top view of a cutting insert according to the sixth embodiment of the present invention. FIG. 19 is a partially enlarged view of the insert mounting seat of the tool body of the cutting tool according to the sixth embodiment of the present invention to which the cutting insert of FIG. 18 is attached. 20 is a view showing a state in which the cutting insert of FIG. 18 is mounted on the insert mounting seat of FIG. FIG. 21 is a top view of a cutting insert according to the seventh embodiment of the present invention. FIG. 22 is a side view of the cutting insert of FIG. FIG. 23 is a top view of a cutting insert according to the eighth embodiment of the present invention. FIG. 24 is a side view of the cutting insert of FIG. FIG. 25 is a top view of a cutting insert according to the ninth embodiment of the present invention. FIG. 26 is a top view of a conventional cutting insert. FIG. 27 is a side view of the cutting insert of FIG. FIG. 28 is a schematic diagram showing a cutting state of a gear by a rotary cutting tool to which the cutting insert of FIG. 26 is attached.

Now, embodiments of the present invention will be described in detail with reference to the drawings. In the following description and drawings, the same reference numerals are used for the same or similar components throughout a plurality of embodiments and the like, and redundant description thereof is omitted.

The cutting insert 10 according to the first embodiment of the present invention has a substantially flat plate shape as shown in FIGS. The cutting insert 10 includes two end faces 12, 14 that are opposite, ie, opposite to each other, and a peripheral side face 16 that extends between the two end faces 12, 14. The cutting insert 10 is provided with a mounting hole 18 extending between and passing through the two end faces 12, 14. The mounting hole 18 has a central axis A extending through the two end faces 12, 14. .

The two end faces 12 and 14 on the opposite side to each other are composed of an upper face 12 as a first end face and a lower face 14 as a second end face. In the cutting insert 10 of the first embodiment, the upper surface 12 and the lower surface 14 are formed substantially in plane symmetry with respect to a plane orthogonal to the central axis A and are formed substantially in parallel. Each of the upper surface 12 and the lower surface 14 is formed to be rotationally symmetric about the central axis A. However, in the cutting insert 10 of the first embodiment, the upper surface and the lower surface are substantially flat surfaces, and are configured to function as insert seating surfaces as described later. However, the upper surface and the lower surface, in particular, the surface portion excluding the edge thereof may have various shapes such as a curved shape and an uneven shape. The upper surface and the lower surface may be reversed, and any of these may be the first end surface or the second end surface. In the present specification, the terms “upper” and “lower” are merely used for convenience of explanation, and do not limit the present invention.

In the cutting insert 10 of the first embodiment, the upper surface 12 has four corner portions 12c and can be regarded as a substantially rectangular shape. The top surface 12 has a pair of long sides 12a as a pair of first edges opposite to each other and a pair of short sides as a pair of second edges opposite to each other. Part 12b, and these edge parts are alternately continued through corresponding corner parts. The long side portion is longer than the short side portion. Each of the long side portions 12a is formed in a convex curve shape so as to protrude outward, and each of the short side portions 12b is formed so as to extend straight. Therefore, the upper surface 12 has a shape that swells outward on the basis of a substantially rectangular shape when the cutting insert 10 is viewed in a plan view, that is, from the side facing the upper surface 12. However, each long side portion 12a is formed so as to extend substantially on a plane defined to be orthogonal to the central axis A, and thus substantially on a plane determined to be orthogonal to the axis A. It is formed to be curved.

Similarly to the upper surface 12, the lower surface 14 has four corner portions 14c and can be regarded as a substantially rectangular shape. The lower surface 14 has a pair of long sides 14a as a pair of first sides on the opposite side to each other and a pair of short sides as a pair of second sides on the opposite side of each other. 14b, and these side portions are alternately continued through corresponding corner portions. Each long side portion 14a is formed in a convex curve shape so as to protrude outward, and each short side portion 14b is formed so as to extend straight. Therefore, the lower surface 14 has a shape bulging outward on the basis of a substantially rectangular shape when the cutting insert 10 is viewed in a plan view, that is, from the side facing the lower surface 14. However, each long side portion 14a is formed so as to extend substantially on a plane determined to be orthogonal to the central axis A, and thus substantially on a plane determined to be orthogonal to the axis A. It is formed to be curved.

The lower surface 14 is substantially plane-symmetric with the upper surface 12 with respect to a plane defined to be orthogonal to the axis A as described above. And when defining the virtual surface extended in parallel with the central axis A so that the long side part 12a of the upper surface 12 may be included entirely, the long side part 14a of the lower surface 14 which exists in the same side of the cutting insert 10 on this surface The upper surface 12 and the lower surface 14 are related to each other such that.

Thus, since the upper surface 12 and the lower surface 14 each have a substantially rectangular shape, the peripheral side surface 16 includes four

side surface portions

20, 22, 24, and 26, and these side surface portions are substantially continuous. In the cutting insert 10, each of these four side surfaces is formed so that most of the four side surfaces extend substantially parallel to the central axis A. The four side portions are from a pair of

first side portions

20, 24 that are opposite, ie, opposite to each other, and a pair of

second side portions

22, 26 that are opposite, ie, opposite to each other. Become. The first

side surface portions

20, 24 extend between one long side portion 12 a of the upper surface 12 and the corresponding long side portion 14 a of the lower surface 14. Further, the second

side surface portions

22 and 26 extend between one short side portion 12 b of the upper surface 12 and the corresponding short side portion 14 b of the lower surface 14. In this way, in the cutting insert 10, since the first side surface portion is associated with the long side portion, it can be hereinafter referred to as the long side portion, and the second side surface portion is associated with the short side portion. , Hereinafter may be referred to as short sides.

In the cutting insert 10, since the long side portion is formed in a convex curve shape so as to protrude outward, the long side surfaces 20, 24 are formed as convex curved surfaces so as to protrude outward. . In particular, the long side portion and the long side surface are formed so that the vicinity of the center portion protrudes most outward. In other words, when the plane P1 extending between the pair of long side portions or long side surfaces 20, 24 of the upper surface 12 or the lower surface 14 and extending so as to include the central axis A is defined, the

long side portions

12a, 14a and the

long side surface

20, 24 are formed so as to be farthest from the plane P1 in the vicinity of the central portion and to approach the plane P1 as the distance from the central portion is increased.

The

long sides

12a and 14a of the upper surface 12 and the lower surface 14 are each formed to have an involute curve shape throughout. Cutting

edges

30 and 32 are formed at the intersecting ridge portions of the upper surface 12 and the peripheral side surface 16, particularly the long side surfaces 20 and 24. Similarly, on the lower surface side 14, cutting

edges

34 and 36 are formed at the intersecting ridge line portion between the lower surface 14 and the peripheral side surface 16, particularly the long side surfaces 20 and 24. The cutting edges 30 and 32 formed at the intersecting ridge line portion between the upper surface 12 and the peripheral side surface 16 can be referred to as first cutting edges, respectively, and the cutting edge 34 formed at the intersecting ridge line portion between the lower surface 14 and the peripheral side surface 16. Each 36 may be referred to as a second cutting edge. However, these names may be reversed. Here, the first cutting edge and the second cutting edge are substantially right-sided with respect to each other except that one is a right-handed cutting edge and the other is a left-handed cutting edge. Have the same structure.

Accordingly, the first cutting edges 30 and 32 extend along the plane P2 defined to be orthogonal to the axis A at the intersecting ridge line portion between the long side surfaces 20 and 24 associated with the upper surface 12, and are orthogonal to the axis A. It is curved in the direction to be. In particular, when the cutting insert 10 is viewed from the side facing the upper surface 12, the first cutting edges 30 and 32 are each formed to have a predetermined first curved shape as an involute curved shape. Similarly, the second cutting edges 34 and 36 also extend along the plane P3 defined to be orthogonal to the axis A at the intersecting ridge line portion between the lower side 14 and the long side surfaces 20 and 24 corresponding to the lower surface 14, and the axis A It is curved in the orthogonal direction. In particular, when the cutting insert 10 is viewed from the side facing the lower surface 14, the second cutting edges 34 and 36 are formed to have a predetermined second curved shape as an involute curved shape. In the present embodiment, the first curve shape and the second curve shape are the same or have a symmetrical relationship, but may be different. When the virtual plane extending in the direction parallel to the axis A is determined so that the first cutting edges 30 and 32 extend on the virtual plane, the long side surfaces 20 and 24 common to the first cutting edges 30 and 32 are formed. The second cutting edges 34, 36 associated therewith extend substantially on this imaginary plane.

As can be understood from the above description, the cutting insert 10 is configured to be able to transfer the involute curve shape to the work material. By using this cutting insert, teeth such as gears, in particular involute gears, can be formed. Since the cutting insert 10 has such a configuration, as will be described later, in order to transfer a specific curved shape such as an involute curved shape to a work material, an insert mounting seat of the tool body is used. The cutting tool is attached with a predetermined inclination with respect to a plane defined to be orthogonal to the rotation axis of the tool main body.

As described above, the cutting insert 10 is formed with two cutting edges for each of the upper and lower surfaces, and has four cutting edges as a whole. Therefore, compared with the cutting insert of patent document 1 which has only two cutting edges, the cutting insert 10 will be remarkably excellent in terms of cost. The two first cutting edges are formed rotationally symmetrically around the central axis A, and the two second cutting edges are formed rotationally symmetrical around the central axis A. Therefore, the cutting insert 10 is an indexable cutting insert.

Also, the upper surface 12 and the lower surface 14 that are the insert seating surfaces are both flat surfaces, and their surface shape (not including the edge) is not limited to the specific curved shape of the cutting edge, and is not limited to the involute curved shape. Therefore, the bottom wall surface in the insert mounting seat of the tool body to which the cutting insert 10 can be attached does not need to have an involute curve shape or a shape corresponding thereto.

Next, a cutting tool to which the cutting insert 10 is detachably attached is shown in FIGS. The illustrated rotary cutting tool 50 is a gear cutter, and a plurality of cutting inserts 10 are attached thereto.

The tool main body 52 of the rotary cutting tool 50 has an annular shape basically composed of two substantially disc-shaped side end surfaces 54 and 56 and an outer peripheral surface 58 extending so as to connect the side end surfaces. I am doing. A rotation axis O can be defined at the center of the tool body 52, and the tool body 52 of the cutting tool 50 is configured to be rotated around the rotation axis O and used.

Along the outer peripheral edge of the annular tool body 52, the

insert mounting seats

60a and 60b to which the cutting insert 10 of the first embodiment is attached are alternately arranged on both end faces. One insert mounting seat 60a may be referred to herein as a first insert mounting seat, and the cutting insert 10 is mounted to use the first cutting edge. The other insert mounting seat 60b may be referred to as a second insert mounting seat here, and is disposed on the side end surface side different from the side end surface side on which the first insert mounting seat is disposed. The cutting insert 10 is attached to the second insert mounting seat 60b to use the second cutting edge.

Further, cutting inserts other than the cutting insert 10 of the first embodiment, here, two types of insert mounting seats on which two types of cutting inserts 62 and 64 are mounted are also provided. Further, chip pockets 66, 68, and 70 are disposed on the front side of each insert mounting seat in the tool rotation direction K. The cutting insert of the first embodiment and the other cutting insert are respectively screwed vertically to each insert mounting seat of the gear cutter 50 having such a configuration.

The rotary cutting tool 50 that is the gear cutter of this embodiment is a type of cutting tool that performs gear cutting by combining a plurality of types of cutting inserts. In this type of gear cutting cutter, there are various cutting inserts that process the vicinity of the base end (bottom) of the tooth gap, cutting inserts that process the vicinity of the center of the tooth groove, and cutting inserts that process the vicinity of the top edge of the tooth groove. Gear cutting is performed using various types of cutting inserts. In the cutting tool 50, the cutting insert 10 according to the first embodiment is used to process the vicinity of the center of the tooth (that is, a portion having an involute curve shape).

For example, when the first cutting edge 30 that is the cutting edge on the upper surface 12 side is used, the cutting insert 10 has its lower surface 14 in contact with the bottom wall surface of the first insert mounting seat 60a and its peripheral side surface. Are attached to the insert mounting seat 60a so that the long side surface 24 and the short side surface 22 which are not associated with the cutting edge thereof abut against the corresponding side wall surface of the insert mounting seat. At this time, the upper surface 12 and the short side surface 26 located on the outer peripheral side function as a flank, and the long side surface 20 having the first cutting edge 30 along the intersecting ridge line portion with the upper surface 12 functions as a rake surface.

On the other hand, for example, when the second cutting edge 34 that is a cutting edge on the lower surface 14 side is used, the cutting insert 10 is arranged so that its upper surface 12 comes into contact with the bottom wall surface of the insert mounting seat 60b and on the peripheral side surface. The long side surface 24 and the short side surface 22 apart from the cutting edge are attached to the insert mounting seat 60b so that they contact the corresponding side wall surfaces of the insert mounting seat 60b. At this time, the lower surface 14 and the short side surface 26 located on the outer peripheral side function as a flank surface, and the long side surface 20 having the second cutting edge 34 along the intersecting ridge line portion with the lower surface 14 functions as a rake surface.

The bottom wall surfaces of the

insert mounting seats

60a and 60b to which the cutting insert 10 is attached are formed with a predetermined inclination. This will be described below with reference to FIG. However, since the two

insert mounting seats

60a and 60b have substantially the same configuration except that they are configured to be plane-symmetric with respect to each other, only the one insert mounting seat 60a will be described below.

The bottom wall surface 60c of the insert mounting seat 60a is inclined with respect to the tool rotation direction K. That is, in the bottom wall surface 60c of one insert mounting seat 60a, the bottom wall surface 60c is formed so that the portion on the tool rotation direction K side is positioned on the outer side. In short, when a plane extending so as to be orthogonal to the rotation axis O is defined, the bottom wall surface 60c is formed with a predetermined inclination with respect to this plane. In FIG. 5, as a plane that extends perpendicular to the rotation axis O, a central plane M that is defined so as to be orthogonal to the rotation axis O and to extend at approximately equidistant positions from both end faces 54 and 56 is provided. It is represented. For example, assuming one cross section in the insert mounting seat 60a to which the cutting insert 10 is mounted, in this cross section, as schematically shown in FIG. 6, the bottom wall surface 60c of the first insert mounting seat 60a has a rotational axis. The distance d between the bottom wall surface 60c and the center plane M in the O direction is inclined so as to become longer toward the tool rotation direction K side. FIG. 6 schematically shows the relationship between the bottom wall surface 60c of one first insert mounting seat 60a and the center plane M with respect to the tool rotation direction K, and the bottom of the second insert mounting seat 60b. The wall surface 60b has an inclination (second predetermined inclination) opposite to the inclination (second predetermined inclination) between the bottom wall surface 60c of the first insert mounting seat 60a and the central plane M (first predetermined inclination).

Therefore, for example, when the cutting insert 10 is mounted on the insert mounting seat 60a with the lower surface 14 as a seating surface, the first cutting edges 30 and 32 having an involute curve shape are formed on the front side in the tool rotation direction formed along the edge. The cutting insert is tilted with the long side surface (that is, the long side surface adjacent to the chip pocket 66) positioned upright from the side end surface of the tool body 52. Also from FIG. 7 which is a partially enlarged view of the cutting tool 50, the long side surface portion S <b> 1 adjacent to or facing the chip pocket 66 of the cutting insert 10 when viewed from the side facing the side end surface 54 of the tool main body 50. It is understood that the cutting insert 10 is tilted and disposed so as to be visible. With such an arrangement, the cutting insert is positioned on the tool body, so that the involute curve can be reliably transferred to the work material.

However, the inclination or the inclination angle of such a bottom wall surface 60c with respect to a plane determined to be orthogonal to the rotation axis O such as the central plane M depends on the cutting edge shape intended to be formed on the work material. Determined. In order to prevent excessive cutting resistance from occurring, the inclination of the bottom wall surface 60c with respect to such a plane is determined so that the rake angle is within a certain range.

In the first embodiment, as shown in FIGS. 1 to 3, the

side portions

20 and 24 that connect the long sides of the upper surface 12 and the lower surface 14 of the cutting insert 10 are formed on the upper surface 12 and the lower surface 14. The cutting insert was configured to extend substantially perpendicular to it. However, the

side surface portions

20 and 24 are not limited to this shape, and may have a shape recessed inward of the cutting insert 10, or may have a shape protruding outward.

In the cutting insert of the first embodiment, the outline shape of the cutting insert 10 in a plan view is basically a substantially rectangular shape, and its long side portion is an involute curve shape. The side or edge to be formed is not limited to this. That is, the present invention allows a form in which such a curved shape is formed on the short side portion. And it is possible to change suitably about the ratio of the length of the long side part and short side part in this same end face. Therefore, a form in which the outer shape of the cutting insert is substantially square in a plan view is also possible. In that case, there is no distinction between a long side and a short side, and a pair of opposing sides can be formed in a curved shape. Further in this regard, it is a basic element of the present invention that the sides formed in a curved shape are a pair of sides facing each other or opposite each other, and the other facing each other. Alternatively, the pair of sides on the opposite side to each other may also be formed in a curved shape. That is, it is possible to adopt a configuration in which all the sides of the substantially square cutting insert are formed in a curved shape in a plan view. FIG. 8 shows a cutting insert 10 ′ according to the second embodiment as an example of the cutting insert having such a configuration.

8 is formed so that the outer shape of the cutting insert 10 ′ is substantially square when viewed from a flat surface. And all the edge parts of substantially square cutting insert 10 'are formed in curve shape in planar view. Note that the present invention does not exclude that all sides of the upper surface or the lower surface are configured to function as cutting edges.

In the first embodiment, the cutting insert 10 is attached to the insert mounting seat of the tool body 52 so that the corresponding surfaces firmly come into contact with each other. However, at least one engaging portion may be provided on one or both of the cutting insert and the tool body. Next, a third embodiment according to the present invention having such an engaging portion will be described.

A cutting insert 110 and a cutting tool 150 according to the third embodiment will be described with reference to FIGS. However, below, it demonstrates regarding the difference with the said 1st Embodiment in 3rd Embodiment, and description of those common matters is abbreviate | omitted.

9 and 10 show the cutting insert 110. In addition to the configuration of the cutting insert 10, the cutting insert 110 further includes recesses 174 that are recessed inward of the cutting insert 10 on the long side surfaces 20 and 24 of the peripheral side surface 16. The recess 174 functions as an engaging portion or a restraining portion when the cutting insert 110 is seated on the

insert mounting seats

60 a and 60 b of the tool body 52.

And as shown in FIG. 11, the protrusion part 176 which can be engaged with this recessed part 174 is provided in the side wall surface 60d of the insert mounting seat 60a of the tool main body 52 of the cutting tool 150. As shown in FIG. Note that the side wall surface 60d is substantially perpendicular to the bottom wall surface 60c of the insert mounting seat 60a having the screw hole 60e. Here, the protruding portion 176 extending from the side wall surface 60d protrudes substantially parallel to the bottom wall surface 60c.

When the cutting insert 110 is attached, the recess 174 of the cutting insert 110 and the protrusions 176 of the

insert mounting seats

60a and 60b of the tool body 52 are fitted together. The cutting insert 110 is more firmly fixed to the tool body 52 by the engagement structure or the fitting structure. Therefore, as in the first embodiment, it is not always necessary to substantially match the shape of the side surface portion of the cutting insert and the shape of the side wall surface of the insert mounting seat, and the tool body of the cutting insert 110 and the cutting tool 150 is not necessarily required. In relation to the 52 insert mounting seat, a certain change in the cutting edge shape is allowed. Therefore, by adopting such an engagement structure, it is possible to attach different types of cutting inserts for forming teeth of different shapes to a common tool body.

In addition, the recessed part formed in the cutting insert is good to change suitably regarding the position and shape. For example, the recess may be shaped taking into account the rake face shape of the cutting insert, and preferably the recess is formed on the peripheral side of the cutting insert to help form a substantially positive rake angle. Good.

Further, although not shown for the cutting inserts 10, 10 ′, 110, chip breakers may be formed on the

side portions

20, 24 as rake faces for the purpose of improving chip disposal. Is possible. The shape of the chip breaker can be appropriately determined in consideration of factors such as the type of workpiece to be cut and the type of cutting insert. Further, for the purpose of improving the strength of the cutting edge, it is possible to form a honing or a land on the cutting edge or a cross ridge line portion where the cutting edge is formed. The shape of the honing and land can also be appropriately determined in consideration of factors such as the type of work material to be cut and the material type of the cutting insert.

The cutting inserts 10, 10 ', 110 may be made from a hard material such as cemented carbide, coated cemented carbide, cermet, ceramic, or ultra-high pressure sintered body containing diamond or cubic boron nitride. it can. The same applies to the cutting insert described below. In addition, the cutting insert which concerns on this invention is not limited to being made from these materials, It can be made from various materials.

In the cutting inserts 10, 10 ′, 110 of the first to third embodiments, the cutting edge is formed so as to substantially extend only at the intersecting ridge line portion between the related end surface and the related side surface portion of the peripheral side surface. It was done. However, the present invention allows other forms of cutting edges that are formed to extend along intersecting ridges between the associated end faces and the associated side portions of the peripheral sides. In other words, the present invention allows various cutting edges that are formed such that at least a part of the cutting edge extends at the intersection ridge line between the associated end surface and the associated side surface portion.

Next, a fourth embodiment according to the present invention will be described. Hereinafter, differences between the first and third embodiments in the fourth embodiment will be mainly described, and descriptions of common matters will be omitted unless otherwise specified. In the fourth embodiment described below, changes similar to those in the first embodiment and the like are allowed in a consistent range, and the fourth embodiment can also achieve the same effects as those in the first embodiment.

As shown in FIGS. 12 to 14, the cutting insert 210 according to the fourth embodiment basically has a shape of the upper surface 12 and the lower surface 14 in a substantially parallelogram shape when viewed from a flat surface. Like the cutting insert 10, each long side portion is formed so as to have an involute curve shape. In the present embodiment, the short side surfaces 22 and 26 that connect the short sides of the upper surface 12 and the lower surface 14 are, as is apparent from FIG. 13, when the cutting insert 210 is viewed from the long side surfaces 20 and 24. The cutting insert 210 is formed in a curved surface projecting outward. Therefore, the upper surface and the short side surface are smoothly connected, and the lower surface and the short side surface are smoothly connected. In FIG. 12, in order to help understanding, the boundary between the upper surface and the short side surface is represented by dotted lines L1 and L2.

Also in the cutting insert 210 of the fourth embodiment, the first cutting edges 30 and 32 extend along a plane P2 defined so as to be orthogonal to the axis A at the intersecting ridge line portion between the upper surface 12 and the long side surfaces 20 and 24. In addition, it is curved in a direction perpendicular to the axis A. In particular, when the cutting insert 210 is viewed from the side facing the upper surface 12, the first cutting edges 30 and 32 are formed to have a predetermined first curved shape as an involute curve. Similarly, the second cutting edges 34, 36 also extend along a plane P 3 defined to be orthogonal to the axis A at the intersection ridge line portion between the lower surface 14 and the long side surfaces 20, 24 and are orthogonal to the axis A. It is curved in the direction. In particular, when the cutting insert 210 is viewed from the side facing the lower surface 14, the second cutting edges 34, 36 are formed to have a predetermined second curved shape as an involute curve. In the present embodiment, the first curve shape and the second curve shape are the same or have a symmetrical relationship, but may be different. When the virtual plane extending in the direction parallel to the axis A is determined so that the first cutting edges 30 and 32 extend on the virtual plane, the long side surfaces 20 and 24 common to the first cutting edges 30 and 32 are formed. The second cutting edges 34, 36 associated therewith extend substantially on this imaginary plane.

In such a cutting insert 210, a cutting edge formed at a crossed ridge line portion in the vicinity of a corner portion (acute angle corner portion) C in which an angle formed between the long side surface and the short side surface is an acute angle or a substantially right angle in a plan view. Is used for cutting the bottom of gears and the like. Therefore, among the intersecting ridge line portions of the long side surfaces 20 and 24 and the short side surfaces 22 and 26, the intersecting ridge line portion 290 adjacent to the acute corner portion also functions as a cutting edge.

In addition to the present embodiment, the short side surface may be formed in a convex shape in the first embodiment as well. In the fourth embodiment, the angle of the acute corner portion and the angle of the obtuse corner portion may be appropriately set in consideration of the type of the work material, cutting conditions, and the like.

15 and 16 show a rotary cutting tool 250 to which the cutting insert 210 of the fourth embodiment is mounted, which is a gear cutter. Unlike the cutting tool 50 described above, the cutting tool 250 of the present embodiment is a type in which only the cutting insert 210 of the fourth embodiment is attached to the tool body 52. In other words, the cutting tool 250 is a type that can process the entire tooth only with the cutting edge formed in the cutting insert 210. Note that such a cutting insert 210 is also attached to the insert mounting seat of the tool body 52 with a predetermined inclination in the same manner as the cutting insert 10 described above.

In the cutting tool 250 of the present embodiment, the cutting insert 210 is mounted on the tool body 52 so that a cutting edge near the corner portion having an acute angle in a plan view of the cutting insert is involved in the cutting. That is, for example, when the cutting insert 210 is detachably attached to the tool body 52 with the upper surface 12 as the flank and the lower surface 14 as the seating surface, the obtuse corner portion of the cutting insert 210 is inserted on the outer peripheral surface side of the tool body 52. The cutting insert 210 is configured such that the sharp corner portion is in an open space on the chip pocket side in contact with the side wall surface of the mounting seat.

In the cutting insert 210, on the upper surface 12 side, the first cutting edges 30 and 32 formed so as to extend along the intersecting ridge line portion between the upper surface and the long side surface are partly formed between the upper surface and the long side surface. In addition to extending to the intersecting ridge line portion, it extends to the intersecting ridge line portion of the long side surface and the short side surface. That is, on the upper surface side, the intersecting ridge line portion between the upper surface 12 and the long side surface 20 and the intersecting ridge line portion between the long side surface 20 and the short side surface 26 function as a series of cutting edges 30, and the upper surface 12 and the long side surface 24 The intersecting ridge line portion and the intersecting ridge line portion of the long side surface 24 and the short side surface 22 function as a series of cutting edges 32. Unlike the cutting insert 10 of the first embodiment, the cutting tool 210 of the first embodiment can cut the vicinity of the base end (bottom) of the tooth with one type of cutting insert 210. The cross ridge line portion between the short side surface 26 and the cross ridge line portion between the long side surface 24 and the short side surface 22 also functions as cutting edges involved in cutting. The second cutting edges 34 and 36 on the lower surface 14 side have the same cutting edge configuration. Therefore, it is possible to use the four cutting edges in combination of the two cutting edges on the upper surface side and the two cutting edges on the lower surface side to transfer the involute curve shape to the work material. In the cutting insert 210 of the fourth embodiment, the cutting edge extending to the intersecting ridge line portion between the long side surface and the short side surface has an involute curve shape in the plan view.

In the cutting insert of the fourth embodiment, since cutting is performed with a cutting edge adjacent to the acute corner portion, the rake angle of the cutting insert when attached to the tool body as compared with the cutting insert of the first embodiment. Can be easily increased, and the edge angle can be reduced. Accordingly, the cutting resistance can be greatly reduced, so that the sharpness can be improved and the breakage of the cutting edge can be greatly suppressed. Therefore, the cutting insert of the fourth embodiment is particularly suitable for a gear cutting cutter that uses only one type of cutting insert that increases the cutting resistance per cutting insert.

As mentioned above, although 4th Embodiment was described, also in the cutting insert of 4th Embodiment, the said recessed part 174 can further be provided similarly to the said cutting insert 110. FIG. FIG. 17 shows a cutting insert 310 of the fifth embodiment provided with a recess 174 in addition to the configuration of the cutting insert 210. However, also in the cutting insert 310, the shape and position of a recessed part can be changed arbitrarily. As described above, the recess is configured such that the protrusion of the corresponding insert mounting seat is fitted, so that the cutting insert 310 can be more firmly fixed to the tool body.

In the cutting inserts 10, 10 ′, 110, 210, 310 of the first to fifth embodiments described above, the curve shape of the cutting edge is an involute curve shape. However, the curved shape of the cutting edge can be a curved shape configured by combining two types of curved portions having two types of curvature, and this configuration has a further practical advantage. FIG. 18 shows a cutting insert 410 according to a sixth embodiment as an example of a cutting insert having a curved cutting edge in which two types of curved portions are combined.

In the cutting insert 410 of FIG. 18, the cutting edge of the long side part of the upper surface and the lower surface has a configuration in which the curvature changes midway. Thus, the following benefits can be obtained by configuring the curved cutting edge from two curved portions having different curvatures.

In the first to fifth embodiments, when the cutting insert is mounted on the tool body, the side wall surface of the insert mounting seat of the tool body and the long side surface of the cutting insert come into contact with each other. It was required to have an involute curve shape that conformed to the shape of the curved cutting edge of the insert (ie, the involute curve). However, since the involute curve is a complicated curve with gradually changing curvature, it is not easy to accurately process the side wall surface of the insert mounting seat into its shape, and the side surface portion of the cutting insert and the side wall surface of the insert mounting seat There may be variations in the contact state with the. That is, there is a limit in improving the fixing property of the cutting insert due to the deviation between the involute curve shape of the side surface portion of the cutting insert and the involute curve shape of the side wall surface of the insert mounting seat. On the other hand, by simplifying the involute curve by approximating the involute curve as a curve having two curvatures as described above, not only the side surface portion of the cutting insert but also the side wall surface of the insert mounting seat can be easily obtained. It becomes possible to form. Therefore, since the side shape of the cutting insert and the side wall surface shape of the insert mounting seat can be more accurately matched, the fixing property of the cutting insert is improved.

As shown in FIG. 18, in the two curved portions of one cutting edge, when the radius of curvature of one curved portion (first curved portion) is R1, the curvature of the other curved portion (second curved portion). The radius R2 is preferably in the range of 0.4R1 or more and less than 1.0R1. This is because if the ratio of the radius of curvature of the two curved portions is out of this range, the degree of approximation of the involute curve will decrease, and the processing accuracy will deteriorate. That is, the above range is a desirable numerical range in which both the fixing property of the cutting insert and the processing accuracy by approximating the involute curve can be achieved. In the cutting insert 410, the first curved portion is positioned closer to the cutting edge tip than the second curved portion. In other words, when the cutting insert 410 is attached to the tool body of the rotary cutting tool, the first curved portion of the same cutting edge is positioned on the outer peripheral side with respect to the second curved portion.

Such an approximate involute curve is not limited to one composed of two curve portions, and can be composed of three or more curve portions having different curvatures. However, in view of manufacturing errors, it can be said that the approximate involute curve is most preferably composed of two curve portions. When comprising three or more curved portions, it is preferable to reduce the contact area between the side wall surface of the insert mounting seat and the side surface of the cutting insert in order to reduce the possibility of such a problem. For example, it is preferable that a part of the side wall surface of the insert mounting seat is formed to be recessed (see FIG. 11), and the side wall surface of the insert mounting seat is configured to contact only a part of the side surface portion of the cutting insert. Of course, even when the approximate involute curve is composed of two curves, this configuration can be adopted.

For example, of the long side surface of the cutting insert, a portion extending between the second curved portion (corresponding portion) of the long side portion of the upper surface and the second curved portion (corresponding portion) of the long side portion of the lower surface (FIG. 18). Can be made to function as a contact surface portion in the cutting insert. In this case, a convex contacted portion S3 that contacts the contact surface portion S2 of the cutting insert can be formed on the side wall surface 60d of the insert mounting seat (see FIG. 19). In FIG. 20, the abutting surface portion S <b> 2 of the cutting insert is brought into contact with the convex abutted portion S <b> 3 of the insert mounting seat 60 a, and the cutting insert 410 is screwed with a mounting screw to the tool body 52. The place where it was installed is shown.

When the approximate involute curve is composed of two curved portions (the first curved portion having the radius of curvature R1 and the second curved portion having the radius of curvature R2), the radius of curvature is employed when the side surface configuration of the insert mounting seat is employed. The length of the curved portion of R2 is preferably longer than the length of the curved portion of the radius of curvature R1. This is because when the cutting insert is attached to the insert mounting seat, the portion related to the curved portion of the curvature radius R2 comes into contact with the side wall surface of the insert mounting seat. This is because it is possible to secure a large contact area with the tool body and improve the fixing property of the cutting insert.

Although a plurality of embodiments have been described above, the combination of the cutting insert and the tool body is not limited to the above. That is, it is also possible to apply the cutting insert 10 of the first embodiment to a gear cutter that performs gear cutting using only one type of cutting insert. Moreover, it is also possible to apply the cutting insert 210 of the fourth embodiment to a gear cutting cutter that performs gear cutting using a plurality of types of cutting inserts.

As described above, in the cutting insert according to the present invention, the upper and lower surfaces that can function as a seating surface do not need to be curved into the curved shape of the cutting edge while forming the cutting edges with respect to the edges of the upper and lower surfaces. Therefore, the shape of the bottom wall surface of the insert mounting seat of the tool body needs to be an involute curve or a curved shape that follows a specific curved shape, as in the case where the conventional cutting insert for gear cutting is simply used on both sides. There is no. Therefore, it is possible to greatly reduce the total cost for gear cutting. At the same time, since it is sufficient to make the bottom wall surface of the insert mounting seat a simple shape such as a flat shape, the bottom wall surface of the insert mounting seat can be processed with high accuracy. Therefore, the cutting insert according to the present invention can be more firmly fixed to the insert mounting seat more easily by mechanical means such as a fastening screw, and the seating stability of the cutting insert is greatly improved.

So far, the cutting insert and the cutting tool that have been formed in a convex curve shape so that the cutting edge of the cutting insert protrudes outward have been described. However, like the cutting insert 510 of the seventh embodiment and the cutting insert 610 of the eighth embodiment shown in FIGS. 21 to 24, the curved shape of the cutting edge is a concave curved shape that is recessed inward of the cutting insert. There may be. However, the cutting insert 510 of FIGS. 21 and 22 has a corresponding relationship with the cutting insert 10 of the first embodiment, and the cutting insert 610 of FIGS. 23 and 24 has a corresponding relationship with the cutting insert 210 of the fourth embodiment. Have By cutting with the cutting edge formed in the concave curve shape in this way, it is possible to form a tooth that can mesh with the tooth formed by the cutting insert of the above embodiment. In other words, it is possible to form a tooth whose side irregularities are reversed, in other words, an involute curve is reversed. Naturally, even such a cutting insert can exhibit the effects characteristic of the present invention described above.

Also in this case, the concave curved shape of the cutting edge can be a curved shape formed by combining a plurality of curved portions having different curvatures, particularly two curved portions. A cutting insert 710 of the ninth embodiment as an example of such a cutting insert is shown in FIG. A cutting insert 710 in FIG. 25 is a modification of the cutting insert shown in FIG. Referring to FIG. 25, in cutting insert 710, when the curvature radius of one curved portion (first curved portion) of two curved portions of the curved shape of the cutting edge is R1, the other curved portion (second curved portion). The radius of curvature R2 of the portion) is preferably in the range of 1.2R1 or more and less than 2.3R1. This is because if the ratio of the radius of curvature of the two curved portions is out of this range, the degree of approximation of the involute curve will decrease, and the processing accuracy will deteriorate. That is, the above range is a desirable numerical range in which both the fixing property of the cutting insert and the processing accuracy by approximating the involute curve can be achieved. In the cutting insert 710 as well as the cutting insert 410, the first curved portion with the radius of curvature R1 is positioned closer to the tip of the cutting blade than the second curved portion with the radius of curvature R2 in the same cutting edge. .

Further, the cutting insert of the present invention is not limited to gear cutting. The cutting insert which concerns on this invention can be used also in the other cutting which aims at forming the process side surface of a workpiece in the shape of a curved surface. That is, the curved edges of the upper surface and the lower surface, that is, the cutting edge, may not have a curved shape intended to transfer the involute curve to the work material.

In the above-described embodiments, the present invention has been described with a certain degree of specificity, but the present invention is not limited to the above-described embodiments. It should be understood that various changes and modifications can be made to the present invention without departing from the spirit and scope of the claimed invention. That is, the present invention includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims.

Claims

A first end face (12) and a second end face (14) opposite to each other, and a peripheral side face (16) extending between the first end face (12) and the second end face (14). A cutting insert comprising a peripheral side surface having two side surface portions (20, 24), and an axis (A) extending through the first end surface and the second end surface is defined.
Two curved first cutting edges (30, 32), one first cutting edge (30) being the first end surface (12) and one side surface portion (20) of the two side surface portions. ) And the one side surface portion so as to function as a rake face, and the other first cutting edge (32) is formed between the first end face (12) and the first edge face (12). Each of the first cutting edges is formed so as to extend along an intersecting ridge line portion with the other side surface portion (24) of the two side surface portions, and the other side surface portion functions as a rake face. A first cutting edge (30, 32) that is curved in a direction perpendicular to the axis (A) at the intersecting ridge line portion with the side surface portion related to the first end surface;
Two curved second cutting edges (34, 36), one of the second cutting edges (34) being the second end face (14) and one of the two side face parts (20 ) And the one side surface portion so as to function as a rake face, and the other second cutting edge (36) has the second end face and the two side faces. Each of the second cutting edges is formed so as to extend along a crossing ridge line portion with the other side surface portion (24) of the portion and the other side surface portion functions as a rake face. The cutting insert provided with the 2nd cutting blade (30, 32) curved in the direction orthogonal to this axis line in the intersection ridgeline part with the side part relevant to 2 end surfaces.
The first cutting edge (30, 32) is formed to have a predetermined first curved shape when the cutting insert is viewed from the side facing the first end surface,
The second cutting edges (34, 36) are formed to have a predetermined second curved shape when the cutting insert is viewed from the side facing the second end face.
The cutting insert according to claim 1.
The first cutting edge (30, 32) and the second cutting edge (34, 36), which are related via a common side part of the two side parts, are arranged to be plane-symmetric. The cutting insert according to claim 1 or 2.
The first cutting edge (30, 32) and the second cutting edge (34, 36) are each formed in a convex curve shape so as to protrude outward. Cutting insert as described in.
The first cutting edge (30, 32) and the second cutting edge (34, 36) are each formed in a concave curved shape so as to be recessed inward. Cutting inserts.
The cutting insert according to any one of claims 1 to 5, wherein the first cutting edge (30, 32) and the second cutting edge (34, 36) are each formed to have an involute curve shape. .
The first cutting edge (30, 32) and the second cutting edge (34, 36) are each formed to have a curved shape formed by combining a plurality of curved portions having different curvatures. The cutting insert according to any one of claims 1 to 5.
Each of the first cutting edge (30, 32) and the second cutting edge (34, 36) has a convex curve shape formed by joining the first curved portion and the second curved portion, respectively. The curvature radius R2 of the second curve portion is in the range of 0.4R1 or more and less than 1.0R1, where R1 is a radius of curvature of the first curve portion. Cutting insert as described in.
Each of the first cutting edge (30, 32) and the second cutting edge (34, 36) has a concave curved shape formed by joining the first curved portion and the second curved portion. The curvature radius R2 of the second curve portion is in a range of 1.2R1 or more and less than 2.3R1, where R1 is a radius of curvature of the first curve portion formed at least partially. Cutting insert as described.
The cutting insert according to claim 8 or 9, wherein a length of the second curved portion is longer than a length of the first curved portion.
The cutting insert according to any one of claims 1 to 10, wherein a concave portion (174) is formed on the peripheral side surface (16).
In the insert mounting seat of the tool body (52) configured to rotate around the rotation axis, the cutting insert has a predetermined inclination with respect to a plane defined to be orthogonal to the rotation axis, The first end surface (12) or the second end surface (14) is detachably attached as a seating surface.
The cutting insert according to any one of claims 1 to 11.
A rotary cutting tool comprising a tool body (52) having two side end faces (54, 56) opposite to each other, the tool body configured to rotate about a rotational axis.
It is the 1st insert mounting seat arrange | positioned in this tool main body in the one side end surface side of the said 2 side end surfaces, Comprising: The 1st insert in which the cutting insert in any one of Claim 1 to 11 is attached A mounting seat (60a);
It is a 2nd insert mounting seat arrange | positioned by this tool main body in the other side end surface side of the said 2 side end surfaces, Comprising: The 2nd insert in which the cutting insert in any one of Claim 1 to 11 is attached A mounting seat (60b),
The first end surface of the cutting insert has a function as an insert seating surface that contacts the bottom wall surface of the first insert mounting seat, and the second end surface of the cutting insert is on the bottom wall surface of the second insert mounting seat. Has a function as an insert seating surface to abut,
When a plane extending perpendicular to the rotation axis is defined, a bottom wall surface of the first insert mounting seat (60a) is formed with a first predetermined inclination with respect to the plane, and the second insert The bottom wall surface of the mounting seat (60b) is formed with a second predetermined inclination with respect to the plane.
Rotary cutting tool.
The cutting insert is a cutting insert according to any one of claims 7 to 10, wherein one curved portion of the first cutting edge (30, 32) and the second cutting edge in each side surface portion of the cutting insert. A portion extending between one curved portion of (34, 36) functions as a contact surface portion,
On the side wall surface of the first insert mounting seat (60a) and the side wall surface of the second insert mounting seat (60b), convex contact portions that can contact the corresponding contact portions are formed, respectively. The rotary cutting tool according to claim 13.
The cutting insert is a cutting insert according to claim 11,
On the side wall surface of the first insert mounting seat (60a) and the side wall surface of the second insert mounting seat (60b), protrusions (176) that can be engaged with the recesses of the cutting insert are formed. The rotary cutting tool according to claim 13 or 14.